1. Field of Invention
The invention relates to a process for determining the alignment of two rotatable machine parts, the use of the process for determining the coupling play between two coupled machine parts, a process for testing a component for straightness along a lengthwise side, a process for determining the alignment of two hollow cylindrical machine parts, and a device for determining the alignment of two rotatable machine parts, the alignment of two hollow cylindrical machine parts or testing a component for straightness.
2. Description of Related Art
In many technical fields, the object is to determine the spatial and/or angular location of two rotatable machine parts, especially two rotating shafts, relative to one another. Thus, for example, in the calibration and adjustment of machine tools, there is a demand for aligning the machine spindles relative to one another with high precision; this assumes exact determination of the relative spatial and angular locations of the spindles to one another. Furthermore, many drive systems have shafts which are coupled to one another for transfer of torque and/or force, and whose relative alignment must be optimized to keep wear of the drive systems as low as possible.
Often, the rotating machine parts to be measured are connected to one another by a coupling element. The relative alignment of the two machine parts thus has a great effect on the operating load of the coupling element. The higher the misalignment of the two machine parts relative to one another, the higher the forces and torques to which the coupling element is exposed during operation. Therefore, it is important to determine the relative alignment of the two rotating machine parts with high precision in order to be able to minimize the angular deviation and the spatial offset between the machine parts by adjustment of the axes of rotation.
Various processes and devices are known for checking, measuring and assessing the relative alignment of two machine parts. For this purpose, for example, reference is made to German Patent Application DE 38 14 466 A1 and corresponding U.S. Pat. No. 6,356,348 B1, German Patent Application DE 101 22 321 A1 and European Patent Application EP 1 248 071 A2.
German Patent Application DE 39 11 307 A1 and corresponding U.S. Pat. No. 5,026,998 disclose a process for ascertaining whether two successively arranged shafts are flush or offset with respect to their center axes. In accordance with this process, a first measurement unit is attached to the first machine part, and a second measurement unit is attached to the second machine part so that a light beam is incident on the detector unit and that a light pattern produced by the light beam is used for determining any misalignment of the axes of the machine parts relative to one another. For determining misalignment, the points of incidence of the light beam on the sensors is used. The measurement signals in the individual measurement angle positions are produced separately for each shaft as signals which are proportional to the distance components which the middle axes of the shafts have from one another in the plane (measurement plane) which is permanently assigned to the respective shaft and which is essentially perpendicular to it in the radial direction which is fixed by the respective measurement position, the measurement angular position. Furthermore, to produce the measurement signals in the individual measurement angle positions of each of the two shafts a measurement pointer is pointed at the shaft which is the other one at the time and which extends in the regions of the pertinent reference element on this acceptance shaft which delivers a signal which corresponds to the radial distance of the middle axis of the measurement pointer from the reference point in the plane of the reference element which is roughly perpendicular to the middle axis of this other shaft.
An especially precise measuring device for determining the alignment of two machine parts using an optical process is described in German Patent Application DE 10 2006 020 358 A1 and corresponding U.S. Patent Application Publication 2007/0253002. This device comprises a light source which emits a repeatedly expanded light beam so that the cross section of this emitted light beam has the shape of cross hairs. The device also comprises a detector unit with at least three sensor arrays or position-sensitive diodes for direct or indirect determination of the incidence points of the light beam which has been expanded in two or more planes. To measure the relative alignment of the two machine parts, the light source is mounted on the first machine part and the detector unit is mounted on the other machine part. If, at this point, the two machine parts are turned synchronously with the light source and detector unit mounted on them, the device of German Patent Application DE 10 2006 020 358 A1 allows high precision determination of the spatial and angular position of the first machine part relative to the second machine part.
European Patent Application EP 1 698 855 A1 and corresponding U.S. Pat. No. 7,486,390 discloses a process for alignment of machines and machine elements or the like, especially of pipes or hollow cylinders, in one of two measurement phases for a fixed light emission and reception device rotation of one reflector prism taking place in at least three optionally selectable rotary positions together with the pertinent data acquisition and in the other of the two measurement phases with a fixed reflector prism rotation of the light emitting and reception device into either two predefined rotary positions which are at a right angle to one another or three or more optionally selectable rotary positions taking place together with the pertinent data acquisition.
However, the known devices are either relative complex or the accuracy of measurement is not especially high.
It also has been established that the measurement is sensitively distorted when there is coupling play between the two coupled machine parts. In this case, the coupling play adulterates the determined values of the relative spatial and angular positions of the two machine parts.